Diabetic retinopathy is the most common cause of new-onset vision loss in young people in the USA and other industrialized countries, and retinal neovascularization is the significant contributory factor to this vision loss. There is a critical need to develop new therapeutic agents and treatment modalities to prevent diabetic retinopathy. The focus of this application is on agents that modulate Tissue Factor (TF)/Vlla interaction. Although TF has been characterized best for its role in blood coagulation, recent studies have suggested a role for this molecule in physiologic processes distinct from homeostasis. Studies from the literature and our own laboratories support our focus on TF modulation as a strategy to regulate pathological angiogenesis. Overview: The studies proposed in Phase I will investigate the efficacy for prevention of ocular neovascularization of compounds which have shown significant inhibition of pro-angiogenic processes and angiogenesis in ovo. Proof of efficacy in Phase I studies will be followed in Phase II by investigation of topical formulations of these agents to study the impact of sustained release formulations on neovascularization in the murine retinopathy of prematurity (ROP) model. In the present application we will pursue strategies to evaluate the efficacy for treatment of retinal neovascularization of Tissue Factor Pathway Inhibitor (TFPI) provided in two ways: 1) directly in the form of recombinant TFPI (r-TFPI), providing an exogenous source of this molecule. 2) Administration of oxidized ultra-low molecular weight heparins (LMWH) with limited to no systemic anticoagulant effects that induce the localized release of TFPI from the endothelium, endogenous production of TFPI. Specific Aim 1. Recombinant TFPI or Oxidized ultra-LMWH (SA Mousa, U.S. Provisional Patent Application Serial No. 60/411,851) will be administered either subcutaneously or by intra-vitreal injection to mice in the ROP model to determine their effectiveness in preventing or attenuating retinal neovascularization. Eyes will be removed and quantification of retinal neovascularization performed. Specific Aim 2. Recombinant TFPI or oxidized ultra-LMWH will be administered to co-cultures of human retinal endothelial cells (EC) with Muller cells exposed to hypoxia/ischemia, and effectiveness in preventing capillary formation will be evaluated by digital image analysis of capillaries stained with EC-specific antibody to CD31-PECAM. [unreadable] [unreadable]